1. Field of the Invention
The present invention relates to a safety device which is suitable for use in starting equipment activated when a vehicle rapidly decelerates, and which is used to enable the starting equipment to be activated and deactivated.
2. Description of the Related Art
As starting equipment activated when a vehicle rapidly decelerates, one used for an air bag apparatus, for example, is known. In this type of starting apparatus, when each of inertial masses is moved inertially upon rapid deceleration of the vehicle, each of ignition pins is moved by an urging force to collide with a detonator, thereby producing a large quantity of gases, with the result that a bag is expanded by the gases thus produced. In addition, one end of an elongated drive shaft extending in the axial direction thereof is brought into contact with a part of the circumferential surface of the inertial mass, whereas the other end thereof extending in the axial direction is brought into contact with a bias pin pressed and urged by each of compression coiled springs, thereby restricting the inertial movement of each inertial mass. Each of the ignition pins is held in engagement with an axially-extending intermediate portion of the drive shaft. The drive shaft is rotatably supported by a vehicle body at the intermediate portion thereof.
This type of starting equipment is provided with a safety device for reliably maintaining the starting equipment at a deactivated state until the air bag apparatus is mounted on a vehicle so as to enable an occupant to ride in his vehicle, and for reliably enabling the starting equipment to be activated in a state in which the occupant can ride in the vehicle. The safety device comprises lock pins and coiled springs. Each of the lock pins is inserted into and disposed in the central part of the starting equipment, and is moved by the force pushing toward the occupant. In addition, a ring-shaped groove is defined in an end of each lock pin on the occupant side, and a hook portion extending in the radial dimension of a coil of each coiled spring is held in engagement with the groove. In this condition, the hook portion of each of the coiled springs extends in the direction normal to each lock pin. The drive shaft is disposed in the leading end of the hook portion so as to be brought into contact with a corresponding portion opposite to a portion of the drive shaft, which is brought into contact with each of balls.
Thus, when each of the lock pins is not pushed forward, the hook portion of each spring serves to inhibit the inertial movement of each ball with the help of the drive shaft, thereby deactivating the starting equipment. On the other hand, when each of the lock pins is pushed forward, the hook portion of each spring is released from the groove defined in each lock pin, so that the hook portion is moved within the plane perpendicular to the axis of each lock pin. As a result, the hook portion and the drive shaft do not interfere with each other, and hence each of the balls can be moved inertially. In other words, the starting equipment is brought into a ready condition.
In this type of safety device, however, pushing force applied in the axial direction of each of the lock pins must be reliably transmitted to the hook portion of each of the springs, which are disposed in the direction normal to each lock pin. More specifically, the direction to input the pushing force must reliably be changed from the axial direction of each lock pin to the direction normal to the lock pin. Thus, the safety device has the problem that when the change in the direction to input the pushing force is not reliably carried out, the accuracy of dimensions and assembly required for respective components such as lock pins, coiled springs, drive shafts and the like must be made more severe because of the possibility of the changeover of either the activation or deactivation of the starting equipment not being suitably carried out.